#define _USE_MATH_DEFINES
#include  <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
#include<math.h>
#include<iomanip>
#include<stdio.h>
#include <stdlib.h>
#include<stdio.h>
#include <queue>
#include<map>
#include <fstream>
#include <sstream>
#include<set>
#include<stack>
#include<time.h>
#include <sys/types.h>
#include <tuple>
#include <numeric>
#include <iterator>

typedef long long int ll;
//#include<bits/stdc++.h>


using namespace std;

ll gcd(ll a, ll b) {
    if (a < b)swap(a, b);
    if (b == 0)return a;
    return gcd(b, a % b);
}
int lcm(int a, int b) {
    return a * b / gcd(a, b);
}


int main()
{

    int Q;
    Q = 1;
    //cin >> Q;
    
    while (Q--) {

        int n;
        cin >> n;
        vector<ll>x(3);
        string p;
        getline(cin, p);
        getline(cin, p);
        for (int j = 0; j < p.size(); j++) {
            if (p[j] == ' ') {
                cout << "assert"; return 0;
            }
            x[0] *= 10;
            x[0] += p[j] - '0';
        }
        for (int i = 1; i < 3; i++) {
            cin >> x[i];
        }
        vector<ll>ans;
        for (int i = 0; i < 3; i++) {
            for (int j = i + 1; j < 3; j++) {
                ans.push_back(x[i] + x[j]);
            }
        }
        sort(ans.rbegin(), ans.rend());
        for (int i = 1; i < ans.size(); i++) {
            if (ans[i] != ans[i - 1]) {
                cout << ans[i]; return 0;
            }
        }
        cout << ans[0];

    }
    return 0;
}